In the assembly of small thermostats, it is well known to employ a plurality of contacts, actuating arms, and ceramic insulators which are placed within the thermostat case. The operating portions of the thermostat, including the contacts and bimetallic arm, are within the thermostat case, while the contact arms extend from the case. All of these components are within a "stack" at the open end of a case. Such a construction is shown, for example, in U.S. Pat. No. 3,223,809--Wehl, assigned to the same assignee as the present invention.
In some instances, a resinous insulating material, such as an epoxy resin, is used to seal the end of the case and this aids in holding the components in place within the "stack." In other cases, no such resinous material is employed. In that case, the parts within the stack must be held within the case by a friction fit. Even when an epoxy is employed, the parts must be held in place so that the epoxy can be correctly applied. Because of the ceramic members, friction fitting is more difficult than if all of the parts were metal. Crimping of the case, after insertion of the "stack" raises the possibility of cracking the ceramic insulating members. Precrimping of the case presents the same problem.
With a live case, one of the thermostat legs is against the case, and an indentation can be provided in this thermostat leg so that, upon insertion, the indentation acts as a spring to hold the "stack" within the case by a friction fit. In many cases, this friction fit is all that is desired or required, though in other cases, the epoxy, or other insulating resinous material can be placed at the opening of the thermostat case, adjacent the stack. Then, the indentation in the thermostat leg holds the various members in their proper position during application of the epoxy material.
With a dead case thermostat, none of the thermostat legs are placed adjacent the case. Thus, this means of frictionally holding the "stack" within the case is not possible. The indentation cannot be provided at a lower point in the "stack," as such as indentation would bear against a ceramic member, rather than the metal case, and provide the same dangers of cracking of the ceramic insulators.